Load delayed seal element, system, and method

ABSTRACT

A seal assembly including, a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface and method.

BACKGROUND

Flow control seals are well known in downhole industries such asdrilling and completion industries and especially so in the hydrocarbonrecovery industry. Those of skill in the art will readily recognize thatall manner of seals are used including compression seals, inflatableseals, etc. for different applications in the downhole environment.

Compression set seals are traditionally fabricated from flexible rubbermaterial. The seals are set by an axial force that may be appliedmechanically by, for example, decreasing the weight of a tubing stringsupported by equipment uphole such as a derrick. Applying an axial forceto the seal expands the seal such that the seal contacts the walls of aborehole. And while compression set seals are some of the oldest seals,and indeed some of the most reliable seals, the art is always receptiveto improvements in performance.

SUMMARY

A seal assembly including, a deformable force transmission portionhaving an inner surface and an outer surface, the force transmissionportion operative to transmit an applied force to a component linked tothe seal assembly, and deformable in a direction transverse to a mainaxis of the seal assembly in response to a increased applied forcegreater than a threshold setting force, and a flexible outer sealportion attached to the outer surface.

A method for sealing a borehole includes applying a first axial force toa seal system operative to actuate a first seal assembly, applying asecond axial force greater than the first axial force operative toactuate a second seal assembly.

A seal assembly system includes a first seal assembly and a second sealassembly each having a deformable force transmission portion having aninner surface and an outer surface, the force transmission portionoperative to transmit an applied force to a component linked to the sealassembly, and deformable in a direction transverse to a main axis of theseal assembly in response to a increased applied force greater than athreshold setting force, and a flexible outer seal portion attached tothe outer surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alikein the several figures:

FIG. 1 is a perspective partially cut away view of an exemplaryembodiment of a seal assembly;

FIG. 2 is a perspective view of an exemplary embodiment of the forcetransmission portion of the seal assembly of FIG. 1;

FIG. 3 is a side cut-away view of the assembly of FIG. 1;

FIGS. 4A-4C illustrate an exemplary method for setting seals;

FIG. 5 is a perspective view of an alternate embodiment of a sealassembly; and

FIG. 6 is an alternate embodiment of a force transmission portion.

DETAILED DESCRIPTION

FIG. 1 illustrates a perspective partially cut away view of an exemplaryembodiment of a seal assembly 10. The assembly 10 includes a deformableforce transmission portion 12, which may be tubular in geometry. Anouter seal portion 14 is positioned adjacent to, and in one embodimentsealed to, an outer diameter surface of the force transmission portion12. An inner seal portion 16 is positioned adjacent to, and in oneembodiment sealed to, an inner diameter surface of the forcetransmission portion. The outer seal portion 14 and the inner sealportion 16 may be formed from a flexible material such as, for example,rubber. The force transmission portion 12 may be formed from metal,plastic, or a composite material. The force transmission portion 12functions to resist a compressive load being applied to the seal 10 sothat the same load may be transmitted thorough the seal 10 in order tobe used downhole thereof. In one iteration, the use to be made of theforce downhole of the seal 10 is as an actuation force. As noted above,compressive forces from uphole of a compressively set seal aretraditionally not available downhole of the seal since those forces arereacted out by the radial expansion of the seal into contact withparametrical walls of the annulus in which they are positioned. Once thecompression set seal is compressed into sealing contact, much if not allof the compressive load from uphole thereof can be borne by thecompression set seal and hence does not transmit therethrough. Becauseof the configuration taught herein including the force transmissionportion 12, compressive setting force can indeed be used downhole of theseal 10. This is effected by delaying the setting of the seal 10.

The seal assembly 10 is capable of transmitting a compressive axialforce through the force transmission portion 12, and due thereto, tocomponents downhole of seal assembly 10. This occurs while a thresholdcompressive force is not achieved whereat the seal 10 will itself set.Therefore depending upon the selected threshold force dictated by theability of the force transmission portion to hold a load without itselfdeforming, other tools including seals, slips, or any other mechanicallyactivated device downhole may be set (at lower threshold loads than theseal 10) prior to seal 10 setting and effectively preventing theapplication of compressive force downhole thereof thereafter. It is tobe understood that multiple seals 10 may be used in a single system withincreasing threshold compression set levels toward a surface locationand setting of all of these is effectible through the compression setconcept noted herein.

After more downhole components are set, the seal assembly 10 may be setby applying a compressive axial force of greater than the thresholdforce to the seal assembly 10 that is sufficient to deform the forcetransmission portion 12. At this point the seal 10 will setsubstantially normally. It is noted that a byproduct of the teachinghereof may be that the seal 10 is energized to a greater degree thantraditional compression set seals because of the embedded forcetransmission portion that will tend to want to stay deformed oncedeformation thereof is effected. This is because it is contemplated thatthe deformation of the portion 12 is plastic deformation somewherebeyond the yield point of the material employed.

While it is to be appreciated that a number of different shaped of forcetransmission portions 12 could be used, as illustrated, the profile ofthe force transmission portion 12 has a greater outer diameter in thecenter of the force transmission portion 12 relative to the ends. Thisencourages a more uniform deformation of the portion 12 thereby avoidingseal contact pressure irregularities. Other embodiments may include aforce transmission portion 12 having a greater outer diameter that isoffset from the center resulting in an asymmetrical profile.

Referring to FIG. 2, a perspective view of an exemplary embodiment ofthe force transmission portion 12 alone, without the balance of the sealassembly 10 provides a greater understanding of the configuration andtherefore working of the portion 12. In the illustrated embodiment,circumferential lines 11 and 13 indicate areas of higher bending stresswhere the portion 12 will tend to yield under compressive load at theselected threshold level.

FIG. 3 illustrates a side cut-away view of the seal assembly 10. Theforce transmission portion 12 has an outer diameter at the center of theforce transmission portion 12 that is greater than the outer diameter ofthe ends of the force transmission portion 12. The main axis of theassembly 10 is represented by line 38.

FIGS. 4A-4C illustrate an example of the operation of an array of sealassemblies 10 in an arrangement 400. Referring to FIG. 4A, a force 4 istransmitted through the tubing string 2 through the seal assemblies 10 aand 10 b such that the force 4 actuates a downhole tool 6 (which couldbe another compression set seal or some other tool responsive tocompressive load). The axial force 4 may be applied mechanically by, forexample, decreasing support of the weight of a tubing string 2 by, forexample, a derrick at the surface (not shown). Referring to FIG. 4B,once the tool 6 is set, the force 4 is increased such that the force isgreater than the threshold setting force of the seal assembly 10 b (butless than the threshold setting force for the seal assembly 10 a);setting the seal assembly 10 b. Referring to FIG. 4C, once the sealassembly 10 b is set, the force 4 is increased above the thresholdsetting force for the seal assembly 10 a, resulting in the setting ofthe seal assembly 10 a.

FIG. 5 illustrates a perspective view of an alternate embodiment of aseal assembly 50 having a force transmission portion 52, an outer sealportion 54, and an inner seal portion 56. The seal assembly 50 issimilar to the seal assemblies described above, however, a forcetransmission portion 52 includes threaded ends 60 that may be used toconnect or link the assembly 50 to downhole and uphole equipment. Thisconfiguration would allow transmission of a tensile force through theseal. Where this force could be used to activate devices either beforeor after the elements were set.

FIG. 6 illustrates another alternate embodiment of a force transmissionportion 70. The force transmission portion 70 comprises a plurality ofribs 72 arranged radially about the rotational axis of a seal assembly.The force transmission portion 70 operates similarly to the forcetransmission portions described above.

While one or more embodiments have been shown and described,modifications and substitutions may be made thereto without departingfrom the spirit and scope of the invention. Accordingly, it is to beunderstood that the present invention has been described by way ofillustrations and not limitation.

What is claimed is:
 1. A seal assembly comprising: a deformable forcetransmission portion having an inner surface and an outer surface, theforce transmission portion operative to transmit an applied force to acomponent linked to the seal assembly, and deformable in response to aincreased applied axial compression force greater than a thresholdsetting force; and a flexible outer seal portion attached to the outersurface.
 2. The seal assembly of claim 1, wherein the assembly furthercomprises a flexible inner seal portion attached to the inner surface.3. The seal assembly of claim 1, wherein the force transmission portionhas a center portion having a greater outer diameter than an outerdiameter of an end portion.
 4. The seal assembly of claim 1, wherein thedeformable force transmission portion has a deformable zone defined by afirst circumferential line and a second circumferential line spacedalong the main axis of the force transmission portion.
 5. The sealassembly of claim 4, wherein the deformable force transmission portionhas a third circumferential line disposed between the first and secondcircumferential lines having a diameter greater than the diameter of thefirst and second circumferential lines.
 6. The seal assembly of claim 1,wherein the force transmission portion is metallic.
 7. The seal assemblyof claim 1, wherein the flexible outer seal portion is a rubber product.8. The seal assembly of claim 1, wherein the force transmission portionhas at least one end having a threaded portion.
 9. The seal assembly ofclaim 1, wherein the applied force is an axial force.
 10. The sealassembly of claim 1, wherein the force transmission portion is tubular.11. The seal assembly of claim 1, wherein the force transmission portionis a plurality of ribs disposed radially about the main axis of sealassembly.
 12. A method for sealing a borehole comprising: applying afirst axial force to a seal system operative to actuate a first sealassembly; and applying a second axial force greater than the first axialforce operative to actuate a second seal assembly.
 13. The method ofclaim 12, wherein the first seal assembly is disposed downhole in theborehole relative to the second seal assembly.
 14. The method of claim12, wherein the first axial force is greater than a first thresholdforce level associated with the first seal assembly and less than asecond threshold force level associated with the second seal assembly.15. The method of claim 12, wherein the method further comprisesapplying a third axial force to the seal system prior to applying thefirst axial force to actuate a tool connected to the first sealassembly.
 16. A seal assembly system comprising: a first seal assemblyand a second seal assembly each having a deformable force transmissionportion having an inner surface and an outer surface, the forcetransmission portion operative to transmit an applied force to acomponent linked to the seal assembly, and deformable in a directiontransverse to a main axis of the seal assembly in response to aincreased applied force greater than a threshold setting force, and aflexible outer seal portion attached to the outer surface.
 17. Thesystem of claim 16, wherein the threshold setting force of the firstseal assembly is greater than the threshold setting force of the secondseal assembly.
 18. The system of claim 17, wherein the first sealassembly is disposed uphole of the second seal assembly.
 19. The systemof claim 16, wherein the threshold setting force of the first sealassembly equals the threshold setting force of the second seal assembly.